The Scottish Association for Marine Science (SAMS) is Scotland's premier independent marine science organisation generating new knowledge for the benefit of the marine environment and society since 1884.

A 100-year record of changing toxic algae in Scottish coastal waters related to change in land use and temperature

HAB-forming dinoflagellates have been affected by climate change. Some species within the Alexandrium tamarense species complex are potent producers of PSP toxins worldwide, including Scottish waters. Routine monitoring of PSP toxins in shellfish around Scotland began in 1991, and since then there have been closures of shellfish sites almost every year. Currently, the Scottish Government is promoting the expansion of the shellfish industry to nearly double its size by 2020, but there is no mechanism to assess the vulnerability of new sites to the impacts of HABs or climate change.

Regional sea surface temperature analyses from 1880 to the present show that temperatures are increasing. However, datasets showing changes in HAB frequency and toxicity cover a much shorter time frame: along Scottish coasts, monitoring for PSP toxins started in 1991 and of Alexandrium spp. in 1996. To address this shortfall in data, this new project will examine dinoflagellate cyst numbers in the sediment record to show changes in species composition over time to compare with changes in climate.

In 2015, we set up a sediment trap in shallow, coastal waters in Shetland and samples have been collected weekly since. Dinoflagellate cysts found in the sediment trap are the link between dinoflagellate cells in the water column and the cysts that fall to the seabed. A sediment trap can therefore be used to find out the rate of encystment, and to give us more information on particle flux, bloom dynamics and the ecology of toxic species. This is particularly important because dinoflagellate life cycles and population dynamics remain poorly understood.

In 2015, we collected sediment samples using a Craib corer and Van Veen grab from 21 stations along the west coast of mainland Shetland. Dinoflagellate cysts will be extracted from those sediment samples and tested for their long-term viability. If large-scale viability is proven, cyst accumulations in certain depositional environments could be acting as seeds beds for blooms. By mapping the seed beds, it would be possible to evaluate the potential risks associated with HABs and climate change, to then inform the aquaculture industry on future siting of activities.

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The Scottish Association for Marine Science (SAMS) has been delivering independent marine science since 1884. Based in Oban, 150 staff are working for healthy and sustainably managed seas and oceans through world-class marine research, education and engagement with society.Learn more about us…